1. Field of the Invention
This invention relates to biological methods and products useful for the control of Solenopsis invicta. More specifically, the present invention is directed to a novel Solenopsis invicta virus, nucleic acids encoding the novel virus, biocontrol compositions, and methods of using the virus and/or biocontrol compositions for control of fire ants.
2. Description of the Related Art
Red imported fire ant, Solenopsis invicta (Buren), was first detected in the United States near Mobile, Ala. in the late 1920s (Loding, USDA Insect Pest Surv. Bull., Volume 9, 241, 1929). Since that time, it has spread to encompass more than 128 million hectares, primarily in the southeastern United States (Williams et al., Am. Entomol., Volume 47, 146-159, 2001). Fire ants are known to destroy young citrus trees, growing crops, and germinating seeds. This has an economic impact on agriculture in infested areas. Telephone companies spend substantial amounts of money each year treating their electrical equipment to prevent fire ant invasion because fire ants accumulate at electrical contacts and can short out electrical equipment. Farm equipment can also be damaged by large fire any mounds. Fire ants also present a danger to wildlife, such as ground nesting birds and animals. Furthermore, fire ants are known to excavate the soil from under roadways causing damage.
Fire ants also pose health care problems to millions of people stung each year—a significant number of which require medical care. Fire ant stings are also blamed for human deaths. Consequently, there is much interest in controlling these troublesome pests.
This interest has resulted in much research and resources being expended through the years to develop reagents and methods for controlling fire ants. While many useful insecticide formulations have resulted from this research, the problems associated with fire ants still exist because the relief gained by insecticide use is only temporary. Once the insecticide pressure is relaxed, fire ant populations invariably repopulate the areas. This reinfestation ability is attributed to the high reproductive capabilities, the efficient foraging behavior, and the ecological adaptability of the ants. While effective for controlling ants in relatively small defined areas, insecticides can create other problems. For example, some insecticides, which are effective at controlling fire ants, can pose a significant threat to the environment, including birds and mammals.
Although considerable research effort has been brought to bear against the red imported fire ant, it remains the primary pest ant species in infested areas; initial eradication trials failed, yielding to the wide distribution of pesticide-based control products and a federally imposed quarantine to prevent further spread. Recently, much of the research effort has focused on elucidating basic life processes in an attempt to develop unique control measures, and fostering the development of self-sustaining methods of control, including biocontrol organisms and microbes (Williams et al., Am. Entomol., Volume 49, 150-163, 2003).
A dearth of natural enemies of the red imported fire ant have been found in the U.S. including a neogregarine (Pereira et al., J. Invertebr. Pathology, Volume 81, 45-48, 2002) and a fungus (Pereira et al., J. Invertebr. Pathology, Volume 84, 38-44, 2004).
U.S. Pat. No. 6,660,290 discloses a non-sporulating mycelial stage of an insect-specific parasitic fungi for control of pests with fire ants listed as one of many examples of insects controlled by the biopesticide.
U.S. Pat. Nos. 4,925,663; 5,683,689; 6,254,864; and 6,403,085 disclose a biopesticide effective against fire ants that includes the fungus Beauveria bassiana. 
There remains a need for biocontrol and/or microbial control agents that eliminate or at least reduce the spread of fire ant colonies using novel pathogens. The present invention described below is directed to a novel Solenopsis invicta virus useful for the control of fire ants which are different from prior art pathogens and their uses.